It is know that to be safely operated, an aircraft cannot be overloaded in terms of weight. Moreover, the balance of an aircraft (i.e., weight distribution) also has to be within certain specifications for the aircraft to be safely operated. For example, if an aircraft is too heavily loaded it may have trouble taking off and/or navigating in certain situations. As another example, if too much weight is in the front of an aircraft (compared to a rear and/or central section of an aircraft), the aircraft may also have trouble taking off and/or navigating in certain situations.
In view of the above, there exists a need in the art for monitoring total weight and weight distribution in an aircraft, to ensure safe operations.
U.S. Pat. No. 6,275,769 discloses a weight and balance calculator for an aircraft. Unfortunately, the system of the '769 Patent relies on data entry (e.g., weight data) from the pilot himself, which can lead to inconsistencies and/or oversights if the pilot is not properly informed.
U.S. Pat. No. 6,237,407 discloses an aircraft weight and center of gravity indication system. Pressure sensors are provided in each of the landing gear struts of the aircraft, and data therefrom is used to determine total weight. See also U.S. Pat. No. 3,513,300. Unfortunately, the system of the '407 Patent is undesirable in that it cannot determine the weight of passengers and luggage per se (i.e., only the total weight of the plane with the passengers and luggage thereon can be approximated). Moreover, the '407 Patent discusses that sensors for measuring the weight on landing gear struts can have problems and not measure the total weight accurately. This can lead to problems in that the pilot cannot determine the total weight of the passengers and aircraft, which can be particularly problematic in situations where the pressure sensors are not properly calibrated or entirely accurate.
For example consider the following situation, where the pressure sensors indicate that the total weight of the loaded aircraft is x and the total permissible weight is x+1%. If the pressure sensor(s) are improperly calibrated or incorrect by 20%, the aircraft can be up to 19% overloaded without the pilot being aware of this. A problem such as this cannot be detected using the system of the '407 Patent which only takes into account the total weight after the passengers and luggage have been loaded onto the aircraft.
In view of the above, it would be helpful for a system to be provided which could determine the total weight of the passengers and luggage on an aircraft, independent of the aircraft itself. If this could be determined, this would reduce the significance of improper calibrations of strut pressure sensors or the like, because the large total weight component of the plane itself would not be considered. Thus, a total weight limit of passengers and luggage could be used to double-check total weight and/or balance requirement of an aircraft in an attempt to prevent situations such as that discussed above from occurring.
Moreover, in certain example embodiments of this invention, a system is provided for detecting when the plane is on non-level ground (e.g., a tilted runway), and for compensating for this non-level ground. This permits more accurate measurements to be made.
In certain example embodiments of this invention, there is provided a method of operating an aircraft, the method comprising: before an aircraft is loaded with passengers and luggage, performing a first measuring to measure a load on front landing gear strut(s) and rear landing gear strut(s) in order to obtain first weight data; after the aircraft has been loaded with passengers and luggage, performing a second measuring to measure a load on front landing gear strut(s) and rear landing gear strut(s) in order to obtain second weight data; subtracting the first weight data from the second weight data, and optionally compensating for fuel added to the aircraft between the times of the first and second measuring steps, in order to determine a total weight of the passengers and luggage on the aircraft; and comparing the measured total weight of the passengers and luggage on the aircraft with a predetermined threshold, and if the measured total weight of the passengers and luggage exceeds the predetermined threshold then actuating an alarm.
In other example embodiments of this invention, there is provided an aircraft comprising: means for, before the aircraft is loaded with passengers and luggage, performing a first measuring to measure a load on front landing gear strut(s) and rear landing gear strut(s) in order to obtain first weight data; means for, after the aircraft has been loaded with passengers and luggage, performing a second measuring to measure a load on front landing gear strut(s) and rear landing gear strut(s) in order to obtain second weight data; means for subtracting the first weight data from the second weight data, and optionally compensating for fuel added to the aircraft between the times of the first and second measuring steps, in order to determine a total weight of the passengers and luggage on the aircraft; and means for comparing the total weight of the passengers and luggage on the aircraft with a predetermined threshold, and if the total weight of the passengers and luggage exceeds the predetermined threshold then actuating an alarm.